Heterogeneity and reproducibility of microvessel counts in breast cancer.

There is a noteworthy heterogeneity in MC between different areas from the same section, between corresponding areas in different sections from the same block, and between different blocks from the same tumor. Consequently, one must carefully scan all the available tumor material in each case for the best hot spot. The hot spot approach is efficient and reproducible, but only a comparative prognostic evaluation can show whether it is clinically more useful than systematic counts.